Phonograph turntable



Sept. 15, 1931. y F. DIEHL 1,823,533

PHONOGRAPH TURNTABLE Filed Oct. l1, 1930 amg/nto@ bederf@ ze/zz Patented Sept. 15, 1931 UNITED STATES PATENT OFFICE FREDERICK DIEHL, OF ELIZABETH, NEW JERSEY, ASSIGNOR TO DIEHL MANUFAC- TURING COMPANY, 0F ELIZABETH, NEW JERSEY, A CORPORATION 0F NEW JERSEY PHONOGRAPH TURNTABLE Application led October 11, V1930. Serial No. 487,935.

-to make the hub of cast metal which was machined and riveted to the turntable disk.

In manufacturing a turntable of this char.

acter it is extremely ditlicult to make the sheet-metal disk run true With the supporting shaft.

According to the present improvement,

the turntable, including its hub, is molded in onepiece, preferably from phenolic condensa-tion material, in a suitable die which has provision for forming a central shaftaperture and enlarged recesses at the opposite ends of the shaft-aperture, arranged on an axis truly perpendicular to the face of the turntable disk. After the molding operation is completed, there are fitted in the recesses at the opposite ends of the shaftaperture, bushings of cork or other comparatively unyielding sound-deadening ma terial adapted to snugly fit the shaft or spindle on which the turntable is mounted; said shaft or spindle being otherwise out of contact with the shaft-aperture in the lturntable.

In the accompanying drawings, Fig. 1 is a side elevation of an electric phonograph motor with the turntable shown in section, and Fig. 2v is a bottom plan view of the turntable supporting disk.

The phonograph motor may be of any suitable or usual construction. The one shown is constructed substantially in accordance with the disclosure of the application of James M. Naul, Serial No. 487,951, filed herewith. It comprises a frame 1 in which is journaled a turntable spindle 2 carrying-a gear 3 meshing with a worm lon the motor-shaft 5. 'lhe motor-shaft 5 is driven by the induction motor G and its speed is governed b v the speed-regulator 7.

` rlhe shaft 2 has passing through it a pin 8 upon which rests a metal disk 9 having the downwardly struck tongues 1() the ends of which engage the pin 8 and lock the disk 9 to rotate with the shaft 2. Resting upon the disk 9 are one or more washers 11 of cork or other sound-deadening material. The turntable disk 12 including its hub 13 is preferably molded in one piece from phenolic condensation material and is-formed with a downturned rim 14 and a. slightly depressed upper face 15 to Which is ee mented a layer of felt 16 the edge of which 1s guarded against peeling by the shoulder 17 Which is disposed slightly above the face The hub 13 is formed with a central shaftclearance aperture 18 the ends of which are enlarged to receive the bushings 19 of sounddeadening material having suflicient body to hold the turntable face 16 truly normal to the axis of turntable shaft 2. The bushings 19 are preferably cemented to the turntable hub 13 and are apertured to snugly fit the shaft 2 which is otherwise out of contact with the hub 13. The bushings 19 should be made from a material which is a poor transmitter of sound but which has considerable resistance to deformation under pressure. Cork is found to have the properties desired here, and will hold the turntable true on the shaft 2 and at the same time prevent transmission to the turntable of any noises originating in the motor, such as magnetic hum or gear noise.

Having thus set forth the nature of the invention, what I claim herein is Y 1. In a phonograph, the combination with a turntable shaft, of a turntable disk having a central hub formed with an axial aperture large enough'to fit over said shaft without touching the latter, and bushings at the opposite ends of said aperture in engagement with said shaft for holding the turntable true tothe shaft, said bushings being formed of a material having poor sound transmission properties and good resistance to deformation under pressure.

2. In a phonograph, the combination With a turntable shaft, of a turntable disk having 5 a central hub formed with an axial aperture large enough to fit over said shaft Without touching the latter, and cork bushings at the opposite ends of said aperture in engagement With said shaft for holding the turntable true to the shaft.

3. A phonograph turntable comprising a disk and hub molded in one piece from phenolic condensation material, said disk having a depressed upper face and a raised rim, a felt facing cemented to said face With its edge in engagement with said raised rim, said hub having a shaft-aperture enlarged at its opposite ends, and bushings of sound-insulating material cemented in the enlarged ends of said shaft-aperture, said bushings having shaft-apertures smaller than the portion of the shaft-aperture in said hub between said bushings.

In testimon7 Whereof I have signed my name to this speoiieation.

FREDERICK DIEHL. 

